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Worrying comment in this months Car Mechanics magazine concerning LED headlights and the MOT test.

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"There have been a few revisions made to the MOT inspection manual in January.Problem was , current MOT testers weren't informed in the usuals way (by notification) of these updates . Since the last update in 2019 there are over 50 revisions to take on board.

Section 4 of the manual is lamps, reflectors and electrical equipment- its fair to say this gets a lot of attention. One of the added checks now required on each MOT is

Compliance with requirements

Existing halogen headlamp units should not be converted to be used with high intensity discharge (HID) or light emitting diode (LED) bulbs. If such a conversion has been done you must fail the headlamp.

The tester did, of course, check on conversions to HID before but the new added text is about fitment of LED bulbs into a halogen housing. As far as I'm aware this revision is for the headlamp bulb itself and won't affect any white LED sidelight bulb fitted to a car. However I'm unsure as to insurance companies views on fitting LED sidelights."

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More bloody stupid rules for the sake of rules. Beam pattern is what matters not technical details of the source. Typical shutting the stable door after the horse has bolted. Plenty of decent LED units that give the right beam pattern around now. Bad ones were an automatic fail before anyway.

Looks as if I ever get round to fitting the pair of LED headlamp bulbs I got a while back I shall have to invest in a beam setter, or, more likely "Clives cheap field expedient equivalent", so I can do swopsies before the MOT.

Clive

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That's a new one, para 4.1.4 in the manual https://www.gov.uk/guidance/mot-inspection-manual-for-private-passenger-and-light-commercial-vehicles/4-lamps-reflectors-and-electrical-equipment. It used to say that you could convert to HID or LED as long as the beam pattern was correct, headlamp washers and wipers were fitted and the car had self levelling suspension or lights. So on a higher spec P38 with the headlamp wash wipe you were OK if you got decent LED bulbs and not the crappy Chinese ones that threw light around everywhere. I suspect they've had to fail so many where LEDs have been fitted to cars that don't have self levelling or the cheapo ones have been used so the beam pattern is wrong (and impossible to get right as on the pair that I tried) that they've decided to make it easy and fail the lot.

I wonder how they will differentiate on things like the modern Mercs that have LED on the higher spec cars or as an option on lower spec ones that ordinarily would have halogen?

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Like other countries have already, everything depends on the original homologation certificate for that vehicle (and they DO have and it is available upon request ...).
So if OEM is LED or Xenon, you can replace them as usual.
If halogen -> stick to halogen.
If you want to convert, if you need to obtain a manufacturer's homologation certificate, or pass a technical inspection where manufacturer's data will be reviewed, or an independent technical body that can authorize the modification (like TUV or Dekra in Germany and Austria).
These norms are standard in most countries (that I know for sure: Spain, Italy, Switzerland, Austria, Germany, Bulgaria).
You guys in the Island have always had a ... unusual approach to these.

That does not remove the fact that probably if the modification is done right, you will be rarely harassed ... I've done over 35k km in the last three years across southern europe with my tri-xenon mod on my A6's headlights, and never an issue whatsoever. And like me, many others ... countless of them :-)

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Over here, as long as a modification doesn't make the car less safe to you or others, then it is OK. With regard to changing headlight bulbs, so many of the cheap Chinese bulbs simply can't be set to give a proper cut off when dipped so are a danger to other road users and I suspect that is why they have taken the blanket approach of just saying if it never had them before it can't have them now. Some things can't be changed, for instance, if a car was fitted with cats when new, it has to have them to pass the test, even if it can pass the emissions test.

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Over here, as long as a modification doesn't make the car less safe to you or others, then it is OK.

This is a very civilized and smart thinking. Unfortunately, most lesser countries - especially European - have decided that the only one empowered to believe how much of an improvement to safety is the manufacturer. This is, if he allows such mod by issuing a specific certificate, then you can validate the mod, otherwise it is "illegal". Now there are some workarounds in the form of independent bodies (such as the TUV I've mentioned above), but not always avaialble in all countries.
As a tinkerer of cars since early age, I have been battling against this backwards mentality since I have memory (over 20 years now), and I see no improvement whatsoever in this mindset.
Approach in later years is I don't care any longer, and I am ready to argument that technically. Luckily for me, I am off the hook, or so it seems .... :-)

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I was aware of the TUV requirements and also the problems with registering a modified vehicle in other countries (Spain and France being the two I'm familiar with). Two people have tried to register LPG converted vehicles in France and Spain and been told that as the LPG conversion was not done by the manufacturer, it had to be completely removed before the car would pass the test. Here, as long as the conversion has been done properly and the car can pass the MoT test and is over 10 years old, then it isn't a problem. Some things that are a problem are rigidly fixed, metal, bull bars for instance, as they make the car less safe to pedestrians when you drive into them, hence the squashy plastic ones.

I noticed the TUV approval system when looking for a replacement exhaust for my partners Merc SLK 280 (3 litre V6 engine). When the time comes, she wants something with a bit more growl to it when she gives it some throttle. I found a German company that do 3 different aftermarket exhaust systems, two are TUV approved but the performance one isn't and is marked as for export only. As long as it retains the cats, is secure, doesn't leak and isn't excessively noisy, then it would pass here irrespective of who made it. I got an MoT pass on a 1340cc Harley Davidson motorcycle (horrible thing to ride but that's a different story) fitted with straight through pipes, no silencing at all. The regulations say that "that the noise emitted from the motorcycle is not clearly unreasonably above the level expected from a similar motorcycle with a standard silencer in average condition" and, as some Harleys came with open pipes as standard, it was not above the level you would expect. It was bloody noisy though......

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Dear All,
Mine has passed two M.O.Ts with all bulbs now LED including the headlights and fogs, no problems.

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@PC38 which HL globes did you use and what are they like? Any tricks or traps?

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Dear David,
These https://www.classiccarleds.co.uk/collections/headlight-led-bulbs very good, a bit fiddly to fit with the heatsink and then zip tie the little black box to the headlamp frame. Work well, good low beam cut off, not absolutely certain they are much brighter as I din't do a side by side but i prefer knowing there's less juice flowing through her 20+ year old wiring.

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What is the actual difference on current with the LEB bulbs ? My understanding is the heatsink is to cool the resistor used to fool the BECM that a regular bulb is fitted & working !! Not sure how low the bulb current can be before triggering the bulb failure detection ?

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Current needed to trigger the build failure warning system depends on how the system works. As I understand it the way P38 electronic control gubbins is fairly close to the CanBus standards. Although, like everything else, the actual magic smoke control is done rather differently from the modern way.

As I understand it CanBus and related, pre Can Bus, systems have three ways of doing the bulb monitoring.

1) Low level pulses to determine if a bulb is actually fitted during the power-up self test on a modern car before everything comes on line and the car can be started. Fortunately doesn't appear to be done on the P38. Things that do tend to need proper CanBus bypass doobies. Although its still a good idea to wait until the self test lights have gone out before starting up.

2) Low current detection circuits to determine if there is an operational bulb. Generally these need to see the something around the impedance of a cold bulb before the drive transistor can turn on. Easily done. From memory the headlamp drive transistors in the BECM have the necessary monitor ability implemented in the device itself hence 4 terminals rather than the usual 3. Osram suggest that a current of around 1/4 the normal, i.e. hot, draw of an operating bulb will suffice. I suspect this is what the P38 uses. Simple, effective and good enough for its purpose.

Pretty sure thats how I worked out the the parallel resistors for the LEDs I put in my reversing lights about 6 years back. Now up to two young active glow worms per light level rather from the standard one geriatric and seriously undernourished glow worm. Better than nowt I guess.

3) Operating current monitoring. The electronics continuously measures the actual current draw of the bulb or illuminator and flags up anything outside that specified for that particular vehicle. We certainly haven't got that although the transistor drive light controls are quite capable of implementing it. In Europe driven by TuV (German) homologation requirements, with a bit of deliberately malicious input from the French, which essentially demand that a modern car has a Car Configuration File of all specification and approved part fitment details hidden in its electronic brain. Anything not on the internal approved list is verboten for that vehicle. So switching stuff from a different specification version becomes a nightmare.

And you thought BECM issues were bad!

Its all getting rather worrying. My second bike is a Yamaha GTS (the funny front end one) and the fraternity are getting reports of German inspection failures when using a 120-70 front tyre instead of the standard 110-70 despite it being an approved alternative fitment because it doesn't actually appear on the original homologation data supplied by Yamaha. It is said the machines are over 10 years old getting the changes approved requires the whole homologation process to be re-run by Yamaha. Which isn't going to happen. Apparently, in Germany at least, the powers exist to invalidate insurance, ban the use of and possibly confiscate anything that doesn't exactly comply with the on file paperwork.

Regrettably pragmatism is out of favour these days.

Clive

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Yes I'm well aware of how the BECM monitors the bulbs using the MosFet outputs. I tried LED reverse bulbs a couple of years ago, but ended up putting them in wife's Freelander !! Just wondered what the actual current is on those with heatsinks, which are clearly there for the resistor rather than the LED.

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Pete12345 wrote:

What is the actual difference on current with the LEB bulbs ? My understanding is the heatsink is to cool the resistor used to fool the BECM that a regular bulb is fitted & working !! Not sure how low the bulb current can be before triggering the bulb failure detection ?

Dear Pete,
Well their web site claims they draw 1.6 amps and the standard Halogens should be drawing about 4.5 amps. Sorry doesn't answer your question though!

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BeCM will also trip out if too much current is drawn, give a Bulb Blown message on the dash and cut the power to that circuit. I was once towing a very big, heavy, trailer so decided to put a 21W equipped amber rotating beacon on it. Easiest way to connect it was to tap into one of the sidelight feeds at the trailer rear light so tapped into that. All fine but after about 10 minutes of driving the dash beeped and told me my NS sidelight was blown. Looked in the mirror and noticed the beacon and the white marker light on the front of the trailer had gone out. Switched the lights off and back on again and they all came back only to shut off with the same warning about 10 minutes later.....

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Clive603 wrote:

Current needed to trigger the build failure warning system depends on how the system works. As I understand it the way P38 electronic control gubbins is fairly close to the CanBus standards. Although, like everything else, the actual magic smoke control is done rather differently from the modern way.

As I understand it CanBus and related, pre Can Bus, systems have three ways of doing the bulb monitoring.

1) Low level pulses to determine if a bulb is actually fitted during the power-up self test on a modern car before everything comes on line and the car can be started. Fortunately doesn't appear to be done on the P38. Things that do tend to need proper CanBus bypass doobies. Although its still a good idea to wait until the self test lights have gone out before starting up.

2) Low current detection circuits to determine if there is an operational bulb. Generally these need to see the something around the impedance of a cold bulb before the drive transistor can turn on. Easily done. From memory the headlamp drive transistors in the BECM have the necessary monitor ability implemented in the device itself hence 4 terminals rather than the usual 3. Osram suggest that a current of around 1/4 the normal, i.e. hot, draw of an operating bulb will suffice. I suspect this is what the P38 uses. Simple, effective and good enough for its purpose.

Pretty sure thats how I worked out the the parallel resistors for the LEDs I put in my reversing lights about 6 years back. Now up to two young active glow worms per light level rather from the standard one geriatric and seriously undernourished glow worm. Better than nowt I guess.

3) Operating current monitoring. The electronics continuously measures the actual current draw of the bulb or illuminator and flags up anything outside that specified for that particular vehicle. We certainly haven't got that although the transistor drive light controls are quite capable of implementing it. In Europe driven by TuV (German) homologation requirements, with a bit of deliberately malicious input from the French, which essentially demand that a modern car has a Car Configuration File of all specification and approved part fitment details hidden in its electronic brain. Anything not on the internal approved list is verboten for that vehicle. So switching stuff from a different specification version becomes a nightmare.

And you thought BECM issues were bad!

Its all getting rather worrying. My second bike is a Yamaha GTS (the funny front end one) and the fraternity are getting reports of German inspection failures when using a 120-70 front tyre instead of the standard 110-70 despite it being an approved alternative fitment because it doesn't actually appear on the original homologation data supplied by Yamaha. It is said the machines are over 10 years old getting the changes approved requires the whole homologation process to be re-run by Yamaha. Which isn't going to happen. Apparently, in Germany at least, the powers exist to invalidate insurance, ban the use of and possibly confiscate anything that doesn't exactly comply with the on file paperwork.

Regrettably pragmatism is out of favour these days.

Clive

(1) and (2) are easy enough to get around with a bit of work, a cheap way is just to wire 12Watt brake light bulbs in parallel with whatever bulbs you're fitting. I once fitted some Xenon's on my dad's 2004 Vectra (this was in 2006), they continuously flashed and the dash lit up with bulb warnings, but they worked perfectly with break bulbs wired in parallel and the dash warning lights went out. Instead of using resistors you can just use bulbs, a resistor flowing same current as a bulb is going to have to dissipate as much heat anyway? Handy under-bonnet lights for checking the engine at night too lol.

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  • a cheap way is just to wire 12Watt brake light bulbs in parallel with whatever bulbs you're fitting. I once fitted some Xenon's on my dad's 2004 Vectra (this was in 2006), they continuously flashed and the dash lit up with bulb warnings, but they worked perfectly with break bulbs wired in parallel and the dash warning lights went out. Instead of using resistors you can just use bulbs, a resistor flowing same current as a bulb is going to have to dissipate as much heat anyway? Handy under-bonnet lights for checking the engine at night too lol.

Simon, pure genius!

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According to this link https://garagewire.co.uk/news/company/osram/osram-canbus-control-unit-resolves-led-bulb-error-messages/ Osram reckon that CanBus and related systems need to see about 1/4 of the current drawn by the proper bulb to stop warnings being triggered.

Which was about what I did for my reversing light LEDs

No great point in exact calculations but if considering headlamps a 48 W bulb draws 4 amps at 12 volts and a 60 W 5 amps. So a parallel resistor drawing around 1 1/2 amps should do the deed. That will be nearly 20 W of heat to get rid of in the resistor. I'd probably go for an 8.2 Ω metal cased wire wound resistor in either 25 watt or 50 watt size. The 25 watt one is smaller but will get rather hotter as having less surface to get rid of the heat. Looking at the fins on my, still unfitted, LED headlamp bulbs they look about right for getting rid of something around 15 - 20 watts in the hot engine compartment. My bulbs claim to use 30 W of power and to work on both 12 and 24 volt systems so the LED driver will be something a bit more sophisticated than a simple dropping resistor. Presumably producing less waste heat.

Its probably good enough to say that reversing lights, stop - tail and flasher bulbs draw 2 amps so the parallel resistor will need to draw around 0.5 amps. Theoretically 24 Ω, 22 or 27 Ω should do. It will need to dissipate 6 W, a 10 w metal cased wire wound will be up to the job.

Osram do their own range of CanBus warning defeat controllers which look just like ordinary metal clad resistors to me. The specified power dissipation isn't vastly out of line with my estimates but it wants more than a quick glance at the data sheet to sort it all out link to the basic data is here https://www.osram.com/ecat/LED%20CANBUS%20CONTROL%20UNIT-LED%20signal%20and%20interior%20lamps-Truck%20lighting-Automotive/com/en/GPS01_2810559/ . The Retrofit Application Overview download shows whats what in relation to the car itself. One to print out and study if really interested, less than screen study friendly. The Exchange overview is basically a list of bulb types.

Interestingly Osram now claim to have TuV approval for their Nightbreaker LED low beam headlamp bulb. Is this the start of proper official recognition?

Clive

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PC38 wrote:

Dear David,
These https://www.classiccarleds.co.uk/collections/headlight-led-bulbs very good, a bit fiddly to fit with the heatsink and then zip tie the little black box to the headlamp frame. Work well, good low beam cut off, not absolutely certain they are much brighter as I din't do a side by side but i prefer knowing there's less juice flowing through her 20+ year old wiring.

Despite being good they as per the original thread an instant M.O.T fail. The tester was quite sanguine he said "its what's fitted when I test it, even if there's an LED wrapped in a plastic bag adjacent to the headlight. What's fitted after you've driven 50 yds down the road is up to you"

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Same as anything else, it's how it is when tested. I've taken imported cars for IVA test with headlights that meet UK spec, only to swap them back to the LHD spec ones after the test (took 7 hours to change the headlights on a Bentley Continental GT Speed and 5 hours to change them back!).